In general, a reciprocating compressor sucks, compresses and discharges gas while a piston performs a liner reciprocating motion inside a cylinder. FIG. 1 is a longitudinal sectional view illustrating the conventional reciprocating compressor.
As depicted in FIG. 1, the reciprocating compressor includes a cylindrical container 10; a reciprocating motor 20 disposed in the container 10 and generating a linear reciprocating driving force; a rear frame 30 and a middle frame 40 respectively supporting the both sides of the reciprocating motor 20; a front frame 50 combined with the middle frame 40; a cylinder 60 fixedly combined with the frame 50 with a certain distance from the reciprocating motor 20; a piston 70 connected to the reciprocating motor 20, inserted into the cylinder 60 and performing a linear reciprocating motion inside the cylinder 60 by receiving the linear reciprocating driving force of the reciprocating motor 20; a compression unit 80 combined with the cylinder 60 and the piston 70, sucking and discharging gas inside the cylinder 60 by a pressure difference generated by the reciprocating motion; and a resonance spring unit 90 for elastically supporting the linear reciprocating motion of the reciprocating motor 20 and the piston 70.
And, the reciprocating motor 20 includes an outer stator 21 having a cylindrical shape and fixedly combined with the rear frame 30 and the middle frame 40; an inner stator 22 inserted into the outer stator 21 with a certain interval; a wound coil 23 combined with the outer stator 21; and a mover 24 inserted between the outer stator 21 and the inner stator 22 so as to perform the linear reciprocating motion.
And, the mover 24 includes a magnetic holder 25 having a cylindrical shape and plural permanent magnets 26 combined with the magnetic holder 25 at regular intervals, herein, the magnetic holder 25 is connected to the piston 70.
And, the compression unit 80 includes a discharge cover 81 for covering a compression space (P) of the cylinder 60; a discharge valve 82 disposed in the discharge cover 81 and opening/closing the compression space (P) of the cylinder 60; a valve spring 83 for elastically supporting the discharge valve 82; and a suction valve 84 combined with the end of the piston 70 and opening/closing a suction path (F) formed inside the piston 70.
And, the resonance spring unit 90 includes a spring supporting rod 91 curved-formed so as to have a certain area and combined with a certain side of the piston 70 or the mover 24 so as to place between the front frame 50 and the middle frame 40; plural front resonance springs 92 placed between the front frame 50 and the spring supporting rod 91; and plural rear resonance springs 93 placed between the spring supporting rod 91 and the middle frame 40.
And, as depicted in FIG. 2, plural spring mounting grooves 91a are formed at the internal surface of the front frame 50 and the front of the spring supporting rod 91 as the number of the front resonance springs 92 to insert-fix the front resonance springs 92 forcibly. In addition, plural spring mounting grooves 92a are formed at the rear of the spring supporting rod 91 and the front of the middle frame 50 to fix the rear resonance springs 93.
In more detail, the resonance spring unit 90 is respectively combined with the both sides of the spring supporting rod 91 in which the mover 24 of the reciprocating motor 20 and the piston 70 are combined together in order to induce the resonance motion of the mover 24 and the piston 70, and it includes the front resonance springs 92 arranged on the piston side and the rear resonance springs 93 arranged on the reciprocating motor side as compression coil springs.
And, plural spring fixation protrusions 94 are respectively formed at the both sides (left and right) of the spring supporting rod 91 in order to insert-fix the front resonance springs 92 and the rear resonance springs 93 forcibly.
In drawings, reference numeral SP is a suction pipe, and DP is a discharge pipe.
Hereinafter, the operation of the conventional reciprocating compressor will be described.
First, when power is supplied to the reciprocating motor 20 and current flows on the wound coil 23, by mutual operation between a flux formed on the outer stator 21 and the inner stator 22 by the current flowing on the wound coil 23 and the permanent magnets 26, the mover 24 including the permanent magnets 26 performs the linear reciprocating motion.
The linear reciprocating driving force of the mover 24 is transmitted to the piston 70, the piston 70 performs the linear reciprocating motion inside the cylinder compressor space (P) and simultaneously the compression unit 80 is operated, and accordingly gas is sucked into the cylinder compression space (P), is compressed and is discharged repeatedly.
And, the resonance spring unit 90 stores-releases the linear reciprocating driving force of the reciprocating motor 20 as elastic energy and induces the resonance motion.
However, in the conventional reciprocating compressor, because the cylinder 60 is combined with the front frame 50, the combining portion between them has to be precisely processed, it is intricate to fabricate the frame 50 and the cylinder 60 precisely, and accordingly assembly productivity is lowered and relatively lots of construction parts are required.
When assembly of the front frame 50 and the cylinder 60 is not precise, due to the assembly error between the piston 70 and the cylinder 60, compression gas may leak or abrasion may occur on the contact portion between the cylinder 60 and the piston 70, interference or contact may occur among the outer stator 21, the inner stator 22 and the mover 24 of the reciprocating motor inserted therebetween, and accordingly parts may be damaged.
In addition, in the conventional reciprocating compressor, by the elastic force owing to the compression coil spring shape, the front resonance springs 92 and the rear resonance springs 93 tend to rotate while repeating compression/relaxation. In that process, because the spring mounting grooves 91a, 92a and the spring fixation protrusions 92 contacted to the resonance springs 92, 93 may be continually worn away, the front and rear resonance springs 92, 93 may deviate from the fixation positions, at the worst the resonance springs 92, 93 may break away, and accordingly reliability of the compressor is lowered.